Analyzer mixing apparatus



May 25, 1965 c. c. HACH ANALYZER MIXING APPARATUS Filed March 25, 1963WW1? m m m /m M United States Patent 3,185,447 ANALYZER MIXING APPARATUSClifford C. Hach, Ames, Iowa, assignor to Hach Chemical Company, Ames,Iowa, a corporation of Iowa Filed Mar. 25, 1963, Ser. N 0. 267,712 3Claims. (Cl. 259-4) This invention relates to automatic continuousanalyzers and more particularly concerns a fluid mixing apparatus forsuch equipment.

An automatic continuous analyzer of an improved kind is shown in mycopending application Serial No. 267,467 filed March 25, 1963. Thisanalyzer reliably mixes a reagent with a fluid sample in controlledproportions and continuously. The resulting mixture is sensed, as forcolor changes with a colorimeter, toobtain the desired test information.

Some reagents blend less readily with a flowing sample than others, andit is sometimes desirable, in making a test, to smoothly blend onereagent into the sample before adding additional reagents.

Accordingly, it is an object of the invention to provide a mixingapparatus for insuring complete blending of one or more reagents, indesired order, into a fluid sample while maintaining controlledproportions of reagent and sample.

A further object is to provide a mixing apparatus of the above characterwhich is simple and compact so as to be well suited for use in aneconomical automatic analyzer.

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings, in which:

FIGURE 1 is a plan of a mixing body constructed in accordance with theinvention.

FIG. 2 is a section taken approximately along the line 22 in FIG. 1; and

FIG. 3 is a fragmentary along the line 3-3 in FIG. 1.

While the invention will be described in connection with a preferredembodiment, it will be understood that I do not intend to limit theinvention to that embodiment. On the contrary, I intend to cover allalternatives, modifications, and equivalents which may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

Turning now to the drawings, there is shown an apparatus for mixing andblending fluid reagents with a less dense fluid sample in controlledproportions. The apparatus includes a mixing body of generallycylindrical shape and including a wall 16 which defines a samplereservoir 17 surrounded by a trough 18 formed between the wall 16 and anouter wall 19.

The body 15 also includes a center block 20 within the sample reservoir17 that is bored to form vertically extend ing mixing passages 21, 22and 23, and to form a discharge passage 24 at approximately the centerof the block 20. The discharge passage 24 is provided with a bottomaperture defined by a tube 25 having a center opening 26. The opening 26is of capillary size or slightly larger, depending upon the sample flowrate desired, as will be discussed below:

A channel 31 connects the bottom of the sample reservoir 17 with thebottom of the mixing passage 21. A channel 32 connects the top of themixing passage 21 to the top of a down passage 33, and another channel34 connects the lower portion of the down passage 33 to the bottom ofthe next mixing passage 22. Similarly, a channel 35 connects the top ofthe mixing passage 22 to the top of a down passage 36, and the bottomportion of the down passage 36 is connected to the bottom of the mixingpas sage 23 by a channel 37. Finally, a channel 38 connects sectiontaken approximately the top of the third mixing passage 23 to the top ofthe discharge passage 24.

Thus, the bottom of the sample reservoir 17 is connected to the bottomof the mixing passages 21-23 through the channel 31 and the passages andchannel preceding the mixing passages 22 and 23. The tops of the mixingpassages 21-23 are connected to the top of the discharge passage 24through the channel 38 and the passages and channels following themixing passages 21 and 22.

The fluid sample is introduced into the reservoir 17 through a port 40at a rate that is greater than the flow rate of the sample through theaperture 26. The channels 32, 35 and 38 lie below the level of the wall16 so that the fluid sample flows from the reservoir 17 through thechannel 31, up the mixing passage 21, over the channel 32, down the downpassage 33, through the channel 34, up the mixing passage 22, and soforth to the discharge passage 24, where the fluid flows through theaperture 26 and is discharged from the apparatus (see the arrows in theseveral figures). Since the fluid sample is added at a rate greater thanit can pass through the aperture 26, the excess fluid spills over thewall 16 into the trough 18 and is carried away through a discharge port41. The wall 16 thus maintains a constant head of fluid relative to theaperture 26 and, hence, the rate of sample flow through the mixing body15 is determined by the size of the aperture 26 in the tube 25.

Two fluid reagents are added to the flow of fluid sample through thebody 15. The first reagent is added through a capillary tube 42extending down into the reservoir 17 and positioned with the tube endadjacent the channel 31. The second reagent is added through a capillarytube 43 disposed in the down passage 36.- The reagent heads are adjustedrelative to the capillary tubes 42, 43 so that reagent flows at adesired rate into the stream of fluid sample. In this way, and bycontrolling the size of the aperture 26, the proportions of fluid andreagent mixed in the body 15 can be adjusted as required by theparticular test to be made.

In operation, the reagents are usually slightly more dense than thefluid sample. The reagent added through the tube 42 thus fallsdownwardly in the reservoir 17 and is carried with the flowing fluidsample through the channel 31. However, the reagent and sample must moveupwardly through the mixing passage 21, and it has been found that theslightly more dense reagent, being carried upwardly by the fluid streammoving in the mixing passage 21, is effectively dispersed and smoothlyblended throughout the fluid sample. It will be noted that the combinedreagent and sample is again carried, via the channels 32, 37 and thedown passage 33, to a second mixing passage 22 which again requires thatthe slightly heavier reagent be lifted by the flowing fluid sample tothe next channel 35. The second upward movement of the sample andreagent insures complete mixing and blending. The stream then movesdownwardly through the down passage 36 and the second reagent is addedthrough the tube 43. This reagent is blended as the fluid flows throughthe channel 37 and upwardly in the mixing passage 23. As a result, thefluid being discharged at a controlled rate through the aperture 26 is asmoothly blended mixture of the fluid sample introduced through the port40 and the two reagents introduced through the tubes 42, 43.

It will, of course, be evident that the order of adding reagents and thenumber of reagents added can be varied, depending upon the test beingperformed. The significant feature of the apparatus is the creation ofan upwardly moving stream of fluid sample to insure complete and smoothblending of the test reagent which has been added to the stream. Thesimplicity, compactness, and economy of the mixing body 15 will bereadily apparent. Those skilled in this art will also appreciate how theapparatus 16 can be embodied in automatic analyzing apparatus of thecharacter shown in my copending application identified above.

I claim as my invention:

1. A one piece mixing body for analyzer apparatus comprising an integralwall defining a sample reservoir, said body having a first hole defininga discharge passage adjacent said reservoir with an aperture at thebottom of the passage, said body having a second hole defining a vertically extending mixing passage adjacent said reservoir and saiddischarge passage, and said body having relieved portions definingchannels interconnecting the bottom of said reservoir with the bottom ofsaid mixing passage and the top of said mixing passage with the top ofsaid discharge passage.

2. In an analyzer, apparatus for mixing and blending a fluid reagentwith a less dense fluid sample in-controlled proportions comprising, incombination, means defining a sample reservoir, a discharge passage, anda mixing pas sage, means providing a bottom aperture in said dischargepassage, means interconnecting the bottom of said reservoir with thebottom of said mixing passage and the top of said mixing passage withthe top of said discharge passage, means for supplying a fluid sample tosaid reservoir at a rate greater than the flow rate through saidaperture, and a capillary tube extending into said reservoir with itslower end adjacent said means interconnecting the bottom of thereservoir for delivering reagent into the stream of sample flowing fromsaid reservoir to said mixing passage.

3. In an analyzer, apparatus for mixing and blending a fluid reagentwith a less dense fluid sample in controlled proportions comprising, incombination, a mixing body having, in horizontally spaced relation, asample reservoir, a discharge passage, and a mixing passage, said bodyhaving a bottom aperture in said discharge passage, said body alsohaving channels interconnecting the bottom of said reservoir with thebottom of said mixing passage and the top of said mixing passage withthe top of said discharge passage, means for supplying a fluid sample tosaid reservoir, and thus to said discharge passage through saidchannels, at a rate greater than the flow rate through said aperture,and a capillary tube extending into said reservoir with its lower endadjacent said channel to said mixing passage for delivering reagent intothe stream of sample.

References Cited by the Examiner UNITED STATES PATENTS 2,440,623 4/48Voorhees 214-152 CHARLES A. WILLMUTH, Primary Examiner.

1. AT ONE PIECE MIXING BODY FOR ANALYZER APPARATUS COMPRISING ANINTEGRAL WALL DEFINING A SAMPLE RESERVOIR, SAID BODY HAVING A FIRST HOLEDEFINING A DISCHARGE PASSAGE ADJACENT SAID RESERVOIR WITH AN APERTURE ATTHE BOTTOM OF THE PASSAGE, SAID BODY HAVING A SECOND HOLE DEFINING AVERTICALLY EXTENDING MIXING PASSAGE ADJACENT SAID RESERVOIR AND SAIDDISCHARGE PASSAGE, AND SAID BODY HAVING RELIEVED PORTIONS DEFININGCHANNELS INTERCONNECTING THE BOTTOM OF SAID RESERVOIRS WITH THE BOTTOMOF SAID MIXING PASSAGE AND THE TOP OF SAID MIXING PASSAGE WITH THE TOPOF SAID DISCHARGE PASSAGE.